An adult stem cell therapy for acute renal failure (ARF) provides insight into how these first generation therapies work. EurekAlert reports that transplanted stem cells are only present briefly, but administer a swift, positive kick to the local environment: "Administered stem cells don't stay in the kidney that has ARF long enough to differentiate into kidney cells, but rather appear to alter the course of ARF by a number of identifiable and some still unexplored paracrine mechanisms. The former include the induction of organ-protective and repair-supporting genes in surviving renal cells, robust suppression of proinflammatory cytokines in the ARF kidney and upregulation of anti-inflammatory genes, as well as the delivery and release at the site of injury of organ-protective and other beneficial gene products by the stem cells."

Link: http://www.eurekalert.org/pub_releases/2005-08/aps-scb081105.php